Heat and Temperature

Review from last class... Did you…? finish the Heat worksheet for homework? put your name on it? put it in the pass in bin? What did you think of Bill Nye- Heat?  best parts?  what do you remember?  confusion or clarifications?

Heat Introductory Worksheet- Answers Part 1: Completing Sentences 1)Energy can make things move 2)Two kinds of energy are heat and electricity 3)Heat is caused by vibrating molecules 4)All matter has heat because molecules are always vibrating. 5)Warm matter has more heat than cold matter. 6)Cool matter has less heat than warm matter. 7)The faster molecules vibrate, the more heat they give off. 8)The slower molecules vibrate, the less heat they give off. 9)Most heat comes from the sun. 10)Rubbing produces heat. Another name for rubbing is friction. Part 2: True and false 1)T2) F 3) F4) F 5)T6) T 7)T8) T 9) F Part 3: Matching: 1)D 2)A 3)E 4)C 5)B Part 4: Word Scramble 1) Energy4) Heat 2) Fuel5)Rubbing 3) Friction

Energy Energy is the ability to do work Energy causes things to happen around us The study of energy is called physics There are many different kinds of energy Heat Energy (Thermal)Chemical Energy Mechanical EnergyElectrical Energy Gravitational EnergyKinetic Energy Potential EnergyNuclear Energy Geothermal Energy Energy does NOT have weight or take up space Energy is NOT matter

Heat vs Temperature What is heat? REMEMBER→ Thermal Energy: the total energy of all the particles in a material or object As long as an object’s particles are moving (which they are in all states of matter) that object has HEAT! What is temperature? Temperature is the average speed of the particle motion in an object (a relative measurement)

HEAT vs TEMPERATURE HEAT AND TEMPERATURE ARE NOT THE SAME THING!

Measuring Temperatures Why measure temperature? How do we measure temperature? Thermometer Thermostats Thermocouple Can you guess the temperatures correctly?

How does a Thermometer work? Many thermometers operate because of expansion and contraction Expansion: increase in the volume of an object or substance For most substances: adding heat causes expansion Contraction: decrease in the volume of an object or substance For most substances: removing heat causes contraction Most solids, liquids and gases follow these principles so almost any substance can be used inside a thermometer

Liquid Thermometers Most commonly found thermometer use the “expansion” and “contraction” of a liquid to measure temperature liquid (usually colored ethyl alcohol) expands when it is warmed up and is forced up the narrow bore of the thermometer the more it is warmed→ higher it goes when liquid cools it contracts, dropping lower in bore

Parts of the Thermometer

Special Clinical Thermometer has a constriction point that restricts the movement as body temperature heats liquid it forces it past this point to show temperature when it’s removed from the patient the liquid can’t move back past the constriction so temperature can be read after it’s taken must be shaken to return liquid back to bulb

The Thermostat used to measure temperature in a room or in an appliance it can also switch appliances on or off at a preset temperature (Feedback system) Use the expansion and contraction of a solid to measure temperature have a “BIMETALLIC STRIP”: a strip made of two metals because the metals are different the expand and contract different amounts causing the strip to bend the amount of bend is dependent on the temperature that bend measures the temperature

Thermostats- FEEDBACK System Thermostat for your furnace Say you want your room to be at 17C, so you set the thermostat As the temperature in the room rises above 17C the bimetallic strip expands which causes the contact point for the circuit to break away, turning the furnace off when the the temperature drops back below 17C, the strip contracts, causing the mercury to flow to the contact, completing the circuit, turning the furnace on

Thermocouple uses electricity to work has two wires, made of different metals that are coupled (joined) at one end when they touch each other it generates electric current the amount of current depends on the temperature the other ends of the wire are connected to a meter that measures electricity the amount of electricity measures the temperature used in very extreme temperatures (higher than a standard thermometer)

Other Thermometers  Recording Thermometer: A bimetallic strip connected to a writing device and paper which records temperature fluctuations over time.  Infrared Thermogram: Records infrared radiation, (heat sensor) as different colors according to their temperature.

Measuring Devices Each device we’ve looked at has a sensor (something that is affected by changes in the environment) the sensor produces a signal (information about temperature, such as electrical current) that affects a responder (a pointer, a light, or other mechanism that transmits the signal in some way)

Types of Thermometer Worksheet 1)Complete the worksheet, put your name on it, put it in the pass-in bin 2)go to gnspes.ca and respond to the exit slip question